1. Field of the Invention
The present invention relates to a thermal printer unit, and particularly relates to a thermal printer unit applied to a printer section of a device.
2. Description of the Related Art
A typical device that has a thermal printer unit installed in its printer section is a POS (Point-of-Sale) device. Label printers for printing labels, which have been widely used in recent years, also have thermal printers installed in their printer sections.
A thermal printer unit 10 as shown in FIGS. 1A and 1B is commonly used for a clamshell type having a curved paper path and is often installed in POS devices. The thermal printer unit 10 is configured to print on a thermosensitive sheet 14 pulled out from a thermosensitive paper roll 13, wherein a thermal head 12 is movable relative to the platen 11.
A thermal printer unit 20 as shown in FIGS. 2A and 2B is often installed in label printers. The thermal printer unit 20 is configured to print on a liner sheet (hereinafter referred to as “label sheet”) 26, which is coated with labels 25, pulled out from a roll 27. The thermal printer unit 20 usually has a thermal head 22 being movable relative to a platen 21 to form a straight paper path, thereby preventing the labels 25 from unexpectedly being released from the label sheet 26.
Most of the thermal printer units for POS devices are designed such that the platen 11 is detachably connectable to the thermal head 12 (see, for example, Japanese Patent Laid Open Publication No. 2000-318260). On the other hand, most of the thermal printer units for label printers are designed such that the thermal head 22 is detachably connectable to the platen 21.
Because of this difference in design, manufacturers of thermal printer units need to produce thermal printer units separately for POS devices and label printers, and therefore suffer from low productivity. Moreover, demand for the thermal printer units for label printers is relatively low compared to the thermal printer units for POS devices, and this further increases the production cost of the thermal printer units for label printers.
Some attempts have been made to develop thermal printer units applicable to both POS devices and label printers. However, thermal printer units designed with a focus on stable operations for the POS devices cannot operate stably when installed in the label printers. Likewise, thermal printer units designed with a focus on stable operations for label printers cannot operate stably when installed in the POS devices. Therefore, dual use thermal printer units have not been put into practical use.